Here at ATV-CC Toulouse, we’re in ‘wait mode’ for tonight’s big event, but in Kourou, teams are busy now with final Ariane 5 launch preparations. It will be the 200th Ariane flight, lofting the sophisticated ATV Johannes Kepler into orbit. ATV-2 is the biggest and heaviest payload ever launched by Europe: Supplies to astronauts aboard the International Space Station and a huge rocket roaring up into the sky has to be one of the greatest shows on Earth!
Ariane update: What’s happening in Kourou?
Just couple of minutes ago, the launch preparations reached the moment when Ariane’s electrical systems were checked. The countdown is a very carefully orchestrated sequence of tasks heading down to the ignition of the main stage engine – followed by the two boosters – for a liftoff at the targeted time. Read more about the launch countdown after the jump (and there’s a perma link at top-right in the blog now to the detailed count-down timeline).
The countdown culminates in a ‘synchronized sequence’, which is managed by the Launcher Control Centre (from the Jupiter Control Room) and by on-board computers starting at T-7 minutes.
If an interruption in the countdown means that T-0 falls outside the launch window, then the launch will be delayed by one, two or more days, depending on the problem involved, while a solution is developed (due to orbital mechanics, delays come in ~24-hour chunks). Hopefully, ATV Johannes Kepler will fly today – at least now all status bars are green!
This is the launch countdown (by main events – detailed timline is available here):
–11h 30 m: Start of final countdown
–7h 30 m: Check of electrical systems
–4h 50 m: Start of filling of main cryogenic stage with liquid oxygen and hydrogen
–3h 20 m: Chilldown of Vulcain main stage engine
–1h 10 m: Check of connections between launcher and telemetry, tracking and command systems
–7m 00s: “All systems go” report, allowing start of synchronized sequence
–4m 00s: Tanks pressurized for flight
–1m 00s: Switch to onboard power mode
–04s: Onboard systems take over
–03s: Unlocking of guidance systems to flight mode
HO Ignition of the cryogenic main stage engine (EPC)
+ 7,0 s: Ignition of solid boosters
+ 7,3 s: Liftoff
+ 12,5 s: End of vertical rise, beginning of pitch motion
+ 17 s: Beginning of roll manoeuvre
+2m 29s: EAP separation
+3m 29s: Fairing jettisoning
+8m 52s: End of EPC thrust phase
+8m 58s: EPC separation
+9m 04s: Beginning of EPS first thrust phase
+17m 17s: End of EPS first thrust phase
+17m 19s: Beginning of ballistic phase
+53m 46s: End of ballistic phase
+59m 28s: Beginning of EPS second thrust phase
+59m 55s: End of EPS second thrust phase
+59m 57s: ATV orientation phase
+1h 3m 54s: ATV separation
+1h 4m 04s: Avoidance and distancing manœuvres
+2h 24m 12s: EPS third boost for deorbitation
2h 44m 39s: End of launch vehicle mission