The Atlantis Countdown Cheat Sheet

This comes to us directly from the Office of Communications at the NASA Goddard Space Flight Center as a reference for some of the main countdown phases in the Atlantis launch on Friday. It should come in handy for those who want to count down with NASA. Please note some terms are in a shorthand of sorts.

As of 8:15 a.m., the launch is moving ahead on schedule. At 8:07 a.m. EDT, the astronauts started to climb aboard space shuttle Atlantis, with liftoff stil slated for 11:26 a.m. EDT.

If, however, the flight is postponed due to unfavorable weather, the information will continue to apply on the new launch day, starting at T-minus 9 minutes.

When it's T-minus, T means time, and the rest means minus whatever amount of time is left until ignition and liftoff.

At lift off, the countdown changes to T+ and starts counting forward from liftoff.

 Launch T- 00:09:00 min.

Resume T- minus count. Final built-in hold terminated

T-00:07:30 min.

Atlantis access arm retracted

T-00:05:00 min.

Hydraulic power system /Auxiliary Power Units  (APU) started

T-00:04:55 min.

Liquid oxygen (LO2) replenish terminated-External Tank

T-00:03:30 min.

Main engines steering test performed

T-00:02:35 min.

Fuel cells go to internal reactants

T-00:02:30 min.

Caution-and-warning memory cleared

T-00:02:00 min.

Crew closes visors

T-00:01:57 min.

Liquid Hydrogen (LH2) tank pressurized

T-00:01:00 min.

Computers verify that the main engines are ready for ignition and the sound suppression water system armed

T-00:00:50 sec.

Solid Rocket Boosters (SRB) joint heater deactivated

T-00:00:31 sec.

Space Shuttle General Purpose Computers (GCP’s)  take control. Go for Auto Sequence Start announced and initiated

T-00:00:21 sec.

SRB steering test

T-00:00:06.6 sec.

Shuttle main engines start

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T-00:00:00

SRB ignition and Lift-off

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T+00:00:10 sec.

Houston takes control of Shuttle (Atlantis) as it clears the tower

T+00:00:20 sec.

Shuttle completes its roll maneuver to aim for rendezvous of the International Space Station (ISS)

T+00:00:40 sec.

Shuttles three main engines are throttled down to 72 percent power to ease the strain on the Atlantis as it passes the region of maximum aerodynamic stress

T+00:00:45 sec.

UHF communications handover from the MILA tracking station to the PDL tracking station (due to the plume affect from the Atlantis to the line of site of the MILA station)

T+00:01:00 sec.

S/band communications handover from the MILA tracking station to the PDL tracking station (due to the plume affect from the Atlantis to the line of site of the MILA station)

T+00:01:10 min.

Shuttles three main engines are throttled up to their 104 percent power setting

T+00:02:10 min.

The SRB’s are jettisoned

T+00:02:15 sec.

UHF communications handover from the PDL tracking station back to the PDL tracking station (plume affect completed)

T+00:02:30 min.

S/band communications handover from the PDL tracking station back to the MILA tracking station (plume affect completed)

T+00:02:35 min.

The Orbital Maneuvering System (OMS) engines are ignited to give the Atlantis an additional boost to help it climb towards orbit (space)

T+00:02:50 min.

JSC Capcom announces to shuttle crew – ‘Two-engine TAL’   (trans Atlantic abort).  If one engine fails, the Atlantis can reach a trans Atlantic abort landing site on just two engines

T+00:03:51 min.

Acquisition of signal (AOS) of the Wallops (WPS) S/band tracking station

T+00:04:00 min.

JSC Capcom announces – ‘ Negative return’. If an emergency landing is required, the Atlantis can not return back to KSC, it will have to land in either Spain or France

T+00:05:00 min.

JSC Capcom announces – ‘ Press to ATO.’ If an engine fails at this point, the Atlantis can still reach low orbit (space)

T+00:06:08 min.

JSC Capcom announces –‘ Press to MECO’ (main engine cut-off). The Shuttle can reach a safe orbit if one engine fails

T+00:07:00 min.

JSC Capcom announces- ‘Single Engine press.’   The Shuttle can now reach orbit on One engine if two engines fail

T+00:07:30 min.

S/band communications handover from the MILA tracking station to the Tracking Data Relay Satellite system (TDRSS). The TDRSS will now be the Prime path for all communications to the Atlantis

T+00:07:45 min.

The three main engines are powered down to ensure the Atlantis does not experience forces greater than 3 g’s

T+00:08:00 min.

Loss of signal (LOS) from the PDL tracking station

T+00:08:12 min.

Loss of signal (LOS) from the MILA tracking station

T+00:08:30 min.

MECO (main engine cut-off) confirmed

T+00:08:44 min.

The emptied ET (external tank) is jettisoned

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T+00:10:00 min.

The Atlantis has reached orbit safely

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T+00:10:13 min.

Loss of signal (LOS) from the WPS tracking station.