Sunday, November 1, 2009

Ares I-X: Countdown 101

Ares I-X at Launch Pad 39B

The Ares I-X flight test will allow NASA to test the Ares I rocket's flight characteristics, hardware, facilities and ground operations. The sub-orbital mission also will verify modeling methods for future designs.

You can share in the excitement of the live countdown via NASA TV or the Web. Coverage begins three hours prior to liftoff, and you can use the countdown events below to track the prelaunch milestones and learn about the Ares I-X countdown process.

T-6 Hours, 40 Minutes
  • Countdown starts.
  • Ares I-X power-up preps begin.
  • Weather balloon released from Cape Canaveral Air Force Station, the first in a series to be released throughout the countdown to evaluate atmospheric conditions such as pressure, humidity, temperature and winds.

T-6 Hours, 30 Minutes
  • Ares I-X power-up begins, a process that takes about an hour.

T-5 Hours, 45 Minutes
  • Launch Test Director Jeff Spaulding receives a weather briefing from Launch Weather Officer Kathy Winters.

T-4 Hours, 55 Minutes
  • First stage igniter and joint heaters are activated.

T-4 Hours, 50 Minutes
  • The vehicle's onboard guidance system, the fault tolerant inertial navigation unit (FTINU), begins a system alignment. This takes about an hour.

T-4 Hours, 10 Minutes
  • Terminate purge of upper stage simulator and first stage avionics module. Environmental control systems that have been proving cool airflow to these areas will be removed, and closeout panels will be installed.

T-3 Hours, 50 Minutes
  • Fault tolerant inertial navigation unit completes alignment and begins navigation testing.
  • Weather balloon release

T-3 Hour, 40 Minutes
  • Prime launch team/Launch Authority Team are on station in Kennedy Space Center's Launch Control Center; the launch support team is on station in Cape Canaveral Air Force Station's Hangar AE.
  • Ground control system (GCS) begins monitoring for commands from the Launch Control Center.

T-3 Hours
  • The rocket's flight termination system, located in the first stage's simulated fifth segment, undergoes hold-fire checks. These checks verify the Eastern Range safety personnel are able to stop the countdown if necessary.

T-2 Hours, 45 Minutes
  • Eastern Range open-loop test.
  • Weather balloon release

T-2 Hours, 40 Minutes
  • Upper stage access arm retraction begins.
  • Live coverage begins on NASA TV and

T-2 Hour, 25 Minutes
  • Upper stage access arm ready for vehicle stabilization system disconnect.

T-2 Hour, 15 Minutes
  • Rotating service structure is rotated to "park."

T-2 Hour, 10 Minutes
  • Launch pad swing arms are unlatched and rotated, signaling the start of work to disconnect the launch pad's vehicle stabilization system.

T-1 Hour, 45 Minutes
  • The rocket's C-band beacon transponder is powered up and tested with the range.
  • Safety personnel begin the process of securing the launch pad.
  • Weather balloon release

T-1 Hour, 30 Minutes
  • Vehicle stabilization system is disconnected and secured for launch.

T-1 Hour, 15 Minutes
  • Ground command, control and communication initiates launch commit criteria monitoring. Known as GC3, the system is located inside the mobile launcher platform and is linked with computers in the firing room.

T-1 Hour, 10 Minutes
  • Launch Test Director weather brief.
  • Technician pulls a lanyard to remove the cover providing weather protection to the five-hole probe (5HP) development flight instrumentation.

T-55 Minutes
  • The fault tolerant inertial navigation unit begins its final alignment after the VSS is retracted.

T-43 Minutes
  • Ares I-X flight termination system is activated and set to "safe."

T-40 Minutes
  • Launch Test Director weather brief.
  • Final status check with solid rocket booster retrieval ships.
  • Assemble and brief post-launch inspection teams.

T-35 Minutes
  • The terminal countdown flight termination system begins its closed loop test.
  • Weather balloon release

T-20 Minutes
  • Final activation of the development flight instrumentation and Tel-4 station.

T-18 Minutes
  • Onboard recorders are activated. A single recorder will collect data from operational flight instrumentation (OFI) and development flight instrumentation (DFI) located on the ground and vehicle.

T-4 Minutes and Holding
  • Countdown clock pauses for a 20-minute built-in hold, the only planned hold in the Ares I-X countdown.
  • Launch weather verification
  • Start launch camera recording, followed by data recording.
  • Option 910, the computer governing the launch sequence, is configured for launch.
  • Launch Vehicle Test Conductor polls his team and reports ready to resume count.
  • Launch Authority Team is polled for launch.
  • First stage igniter heater power removed.
  • Launch Test Director Jeff Spaulding conducts final launch status verification.

T-4 Minutes and Counting
  • Countdown resumes at T-4 minutes.
  • Ares I-X flight termination system and solid rocket motors are armed. (T-3 minutes, 30 seconds)

T-3 Minutes
  • Fans cooling the first stage avionics module and upper stage simulator are turned off.

T-2 Minutes
  • Ares I-X transfers to internal power. (T-1 minute, 59 seconds)
  • Onboard operational and developmental flight instrumentation recorders are started. (T-1 minute, 54 seconds)
  • The rocket's flight control system is enabled for launch. (T-1 minute, 40 seconds)
  • Flight control system switches to internal power and receives the start count from the GCS. (T-1 minute, 20 seconds)

T-1 Minute
  • Solid rocket motor joint heaters are deactivated. (T-50 seconds)
  • Flight control system switches to navigation mode, and inertial and navigation data are verified for accuracy. (T-35 seconds)
  • Auxiliary power units are started. (T-28 seconds)
  • Solid rocket motor thrust vector control gimbal test is performed. (T-21 seconds)
  • Ignition and hold-down bolts are armed. (T-18 seconds)
  • Ground control system issues commands for sound suppression, opening the valves to flood the mobile launcher platform with water. At its peak, water will flow at a rate of 900,000 gallons per minute. (T-16 minutes)
  • Launch inhibits are removed and vehicle is armed. (T-10 seconds)

  • Liftoff!
  • Ares I-X begins a 20-second "fly-away" steering maneuver designed to take the rocket away from the launch tower to minimize damage to the launch pad.

NASA's John F. Kennedy Space Center